The invention relates generally to methods and apparatus for drilling and coring earth formations and, more particularly, to improvements in the coring system disclosed in Bodine U.S. Pat. No. 4,836,299 for Sonic Method and Apparatus for Installing Monitor Wells for the Surveillance and Control of Earth Contamination. The disclosure in U.S. Pat. No. 4,836,299 (the '299 patent) is incorporated herein by reference.